Insects, which are invertebrates have metabolism pathways or immune systems that are different from those of a vertebrate, and they exhibit resistance to pathogens or viruses based on strong natural immunity caused by various physiological substances synthesized in a living organism. Furthermore, by their ecology, insects also form a specific relationship with an external system, for example, other living organisms, pathogens, viruses, or the like. For such reasons, studies are under progress in recent years regarding the physiologically active substances that are derived from the insects or their ecology, and a large number of compounds having novel structure which have not been known before are being found.
As one background of the above, the inventors of the present invention have continuously performed a study on a pharmaceutical effect of plant worms and the like until now.
With regard to the classification and name of the plant worms, the phylogenetic relationship has been discussed and naming has been made all together while the morphology has been conventionally considered as a main aspect and expression of mating performance, ecology, pathogenic property, chemical classification, or the like is used as an indicator. Currently, based on molecular phylogenetic classification which uses a genotype as an indicator, a new classifying system is being constructed and established by determining again the phylogenetic relationship between Cordyceps genus and Clavicipitaceae family and also by considering the morphological characteristics. Accordingly, in the explanations that are given below, the Japanese name of the plant worms based on the descriptions of An Illustrated Guide to Ecology of Japanese Cordyceps (2014, published by SEIBUNDO SHINKOSHA) is described, and for those described for the first time, both the conventional name of species and the name of the species based on new classification are given in parentheses.
Cordyceps is one of the insect pathogen fungi sticking on an insect, and according to the interpretation in narrow sense, it indicates Cordyceps sinennsis (also referred to as Cordyceps sinennsis or Ophiocordyceps sinennsis) which lives in a high mountain area at 3,000 to 4,000 meters altitude in Nepal or Bhutan as well as Tibet Autonomous Region, Quinghai Province, Sichuan Province, Guizhou Province, Gansu Province, and Yunnan Province of China and it has, as a host, Endoclyta excrescens Butler belonging to Insecta, Lepidoptera, Hepialoidea, or Hepialidiae. There are various types of the host insect in a broad range in which Hemiptera, Lepidoptera, Coleoptera, Hymenoptera, Orthoptera, Odonata, and Diptera are included.
Incidentally, according to the interpretation in broad sense, the entire parasitic fungi living on adults or larvae of those insects are also referred to as the plat worms.
In addition, there is only little scientific knowledge available regarding the plant worm as a material for oriental medicine or a material for health supplementary food. Nevertheless, as an exemplary study on the physiological activity of the plant worms until now, Cordyceps sinennsis and a product thereof are widely used as a nutritional supplement which is effective for preventing diabetes, a cardiovascular disease, cancer, or a metabolism disease, or delaying the progress of those diseases (Non Patent Literature 1). Other than that, there are reports showing an anti-oxidation activity (Non Patent Literature 2), an immune-modulating activity (Non Patent Literature 3), an in vivo activity of lowering insulin resistance and enhancing insulins secretion in vivo (Non Patent Literature 4) by a water extraction of SANAGITAKE (Cordyceps militaris), an anti-hyperlipidemic effect (Non Patent Literature 5), an anti-cancer activity (Non Patent Literature 6), and an anti-inflammatory activity (Non Patent Literature 7) of a hot water extraction of Cordyceps sinennsis, which is Cordyceps found in Tibet. Furthermore, also according to a very recent report, it is shown that a physiologically active substance like cordycepin isolated from Cordyceps sinennsis has a novel physiological activity which has not been reported before (Non Patent Literatures 8 to 10). According to over-collecting due to a rapidly increasing demand based on such high popularity of Cordyceps, Cordyceps sinennsis from Tibet becomes highly expensive and is difficult to obtain.
Furthermore, since Paecilomyces tenuipes (also referred to as Isaria japonica Yasuda) as one type of the plant worms according to the interpretation in broad sense belongs to Cordyceps sp. of Cordyceps family of Ascomycetes and it is a parasitic fungus found on larvae or pupae of silkworm (Bombyx mori, and will be described as B. mori hereinbelow), artificial culture of Cordyceps based on combination with pupae of B. mori are recently commercialized in Japan. However, many commercially available products of the plant worms of Cordyceps sp., genus Paecilomyces and genus Isaria are mostly produced based on mycelial culture of asexual species, and also the research reports regarding the pharmaceutical effect of Paecilomyces tenuipes are significantly fewer than those regarding Cordyceps sinennsis. 
As a physiologically active component of Paecilomyces tenuipes that is known until now, there is spirotenuipesine A and B which are obtained by drying and preparing in powder form a fruiting body of Paecilomyces tenuipes which has been cultured in a medium added with cereals, cereals or yeast or an extract thereof followed by extraction with 70% methanol and distribution with ethyl acetate and water, performing distribution of an aqueous phase with n-butanol and water, and treating an n-butanol phase with silica gel chromatography followed by elution with ethyl acetate (Patent Literature 1). Also known is cyclic hexadepsipetide Beauvericin which is isolated from an ethyl acetate extract of a mixture powder of a host (i.e., B. mori pupa) and a fruiting body and has an effect of inhibiting proliferation of rat cancer cells (Non Patent Literature 11), and hanasanagin (3,4-diguanidinobutanoyl-DOPA) which is obtained by using a fruiting body isolated from a host (i.e., B. mori pupa) as a raw material and performing the processes of 60% ethanol extraction, 5% methanol extraction, and hot water extraction, and has an activity of scavenging free radicals (DPPH) or an activity of scavenging superoxide anions (Non Patent Literatures 12 and 13).
Furthermore, the inventors of the present invention found that, while conducting a study on Paecilomyces tenuipes that is easier to obtain than Cordyceps sinennsis and thus is excellent in terms of cost and stable supply, an extraction fraction derived from powder of Paecilomyces tenuipes has an effect of improving the cerebral function of a mammal or has an activity of strongly promoting the proliferation of an astrocyte (Patent Literatures 2 and 3). Accordingly, inventors of the present invention continuously conducted additional intensive studies on the relationship between the astrocyte proliferative activity and Paecilomyces tenuipes. 
An astrocyte (i.e., star-like glial cell) as one kind of glial cells makes up about a half of the entire cells in brain. From the viewpoint that the information processing function is carried out by a neuronal cell, it has been conventionally considered that the astrocyte present near neuronal cell has a function of supporting and protecting a neuronal cell, and supplying nutrients to the cell.
Incidentally, it has been demonstrated that the astrocyte itself participates in the cellular information processing because now there are reports suggesting that the astrocyte is a supplementary system for indirect forming of a neural network having an activity of forming a neural network (Non Patent Literatures 14 to 17) and an activity of regulating a transmitter concentration (Non Patent Literatures 18 and 19), and also it is capable of having an input from a neuronal cell and subsequent calcium propagation between astrocytes (Non Patent Literatures 20 to 22) and having an output to a neuronal cell including a synapse vesicular vesicle (Non Patent Literatures 23 and 24).
Furthermore, a study on the role of an astrocyte in forming of memory is also now carried out, and a higher brain function like memory is considered to be controlled by an interaction between a neuron and an astrocyte. For example, it is reported that the number of astrocyte increases in a hippocampus after forming of memory (Non Patent Literature 25) and forming of memory is inhibited if the function of an astrocyte is suppressed (Non Patent Literature 26).
Furthermore, as an abnormality in terms of anatomy of cerebral nerves which is commonly shown in a mental disease like an integration dysfunction syndrome, bipolar disorder, and depression, an enlargement of brain ventricle, and shrinkage of hippocampus and cerebral cortex size are seen at macro level. At micro level, shrinkage of a size of neuronal cell body, a decrease in density of dendritic spine, shortening of dendrite length, and a decrease in synapse-related proteins are known. They are considered to be a direct abnormality of a neuronal cell. However, it is reported recently that a decrease in the number of astrocyte is also commonly observed, and the possibility of having an indirect abnormality in neuronal cell state which is based on a decrease in the number of astrocyte is also determined (Non Patent Literature 27).